JP6488430B2 - Vinylidene fluoride resin fiber and sheet-like structure - Google Patents

Description

  The present invention relates to a vinylidene fluoride resin fiber and a sheet-like structure.

  Since vinylidene fluoride resin has high mechanical properties, it is being developed as being applicable to various fields.

  For example, Patent Document 1 discloses a vinylidene fluoride resin molded product having a large Young's modulus and excellent surface properties and transparency.

  Patent Document 2 discloses a vinylidene fluoride resin having improved tensile strength and a method for producing the same.

  Patent Document 2 discloses a method of obtaining a filament by spinning a vinylidene fluoride resin at a high draft rate without going through a stretching step.

Japanese Patent Publication “JP 59-41310 A” (published March 7, 1984) Japanese Patent Publication “Japanese Unexamined Patent Publication No. 60-28510 (published on February 13, 1985)”

  However, when spinning by the method described in Patent Document 2, since the necking in which the filament is deformed by stress and the thinning of the filament that are thinning progress rapidly on the spinning line, the molecular chain is oriented and unoriented. There is an amorphous part that is thinned as it is. Therefore, the fiber obtained by using the filament in which many unoriented amorphous parts are present has a problem that the thermal shrinkage rate is lower than that of a normal drawn yarn.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize a vinylidene fluoride resin fiber having excellent mechanical properties such as strength and high thermal shrinkage.

  The present inventors have found that a factor that improves mechanical properties is the presence of a rigid amorphous part. Further, the present invention has been completed by finding that the rigidity of the amorphous portion is expressed and the thermal contraction rate is increased in the process of the progress of the orientation, in other words, in the process of increasing the orientation degree. The present invention can be expressed as follows.

  The vinylidene fluoride resin fiber of the present invention is a fiber using a plurality of vinylidene fluoride resin filaments, and the fiber has a glass transition temperature of −28 ° C. or higher and a heat shrinkage rate at 100 ° C. Is 2% or more.

  The sheet-like structure of the present invention is formed using the vinylidene fluoride resin fiber of the present invention.

  According to the present invention, it is possible to provide a vinylidene fluoride resin fiber having excellent mechanical properties such as strength and high heat shrinkage rate.

  Hereinafter, an embodiment of the vinylidene fluoride resin fiber of the present invention will be specifically described.

<Vinylidene fluoride resin fiber>
The vinylidene fluoride resin fiber (hereinafter also simply referred to as “fiber”) according to the present embodiment is a fiber using a plurality of vinylidene fluoride resin filaments, and the fiber has a glass transition temperature of −28. The heat shrinkage rate at 100 ° C. is 2% or more.

[filament]
In this specification, a filament means one single yarn. The vinylidene fluoride resin filament (hereinafter also simply referred to as “filament”) according to the present embodiment means a filament made of a vinylidene fluoride resin. The vinylidene fluoride resin will be described later in detail.

  What is necessary is just to set the length of the filament which concerns on this embodiment suitably according to the length of a fiber.

  In addition, the diameter of the filament according to the present embodiment may be appropriately set according to the use of the fiber, etc., but the diameter of the filament is preferably 5 μm or more and 80 μm or less, more preferably 10 μm or more and 60 μm or less. More preferably, it is 12 μm or more and 40 μm or less.

  In addition, in this specification, the length of a filament refers to the size of the longitudinal direction of a filament. Moreover, the diameter of a filament refers to the size in the direction orthogonal to the longitudinal direction of a filament.

[Fiber]
The fiber according to the present embodiment refers to a fibrous structure using a plurality of vinylidene fluoride resin filaments. The fiber of this embodiment is formed by integrating a plurality of filaments, and generally means a form called a multifilament.

  The number of filaments according to the present embodiment may be set as appropriate according to the use of the fiber and is not particularly specified.

  What is necessary is just to set the length of the fiber which concerns on this embodiment suitably according to the use etc. of a fiber.

[Glass-transition temperature]
In the present specification, the glass transition temperature (hereinafter also referred to as “Tg”) indicates an onset temperature at which the stiffness and viscosity of the fiber change. That is, it can be said that since the micro-Brownian motion of the molecular chain starts when the glass transition temperature is exceeded, the amorphous part starts to move. Usually, it appears in the vicinity of −40 ° C. in homopolymerization of vinylidene fluoride. That is, the appearance of the glass transition temperature on the higher temperature side means that the temperature range in which the amorphous part moves is high, which reflects the rigidity of the amorphous part.

  In the fiber according to the present embodiment, the glass transition temperature is −28 ° C. or higher, so that the amorphous part in the fiber is highly oriented, and as a result, the rigidity of the fiber of the present invention is exhibited.

  In addition, the said glass transition temperature does not change with the number of the filaments which the fiber which concerns on this embodiment has.

  The glass transition temperature of the fiber according to the present embodiment may be −28 ° C. or higher, preferably −26 ° C. or higher, more preferably −23 ° C. or higher, and further preferably −20 ° C. or higher. It is preferable that the glass transition temperature is within this range from the viewpoint of further improving the rigidity of the amorphous part.

  The glass transition temperature can be controlled by manufacturing conditions when manufacturing the fiber according to the present embodiment. A specific control method will be described later.

  In this embodiment, the glass transition temperature can be obtained from dynamic viscoelasticity measurement. Specifically, using a dynamic viscoelastic device, the test sample length is set to 3 mm, the frequency is set to 4 points of 0.5, 1.0, 5.0, and 10 Hz, and the measurement temperature range is −100 ° C. to 180 ° C. Temperature rise rate: measured at 2 ° C./min, and the glass transition temperature (Tg) is defined as the peak temperature of dispersion derived from Tg appearing at a frequency of 10 Hz.

[Heat shrinkage]
In the present specification, the heat shrinkage rate is a ratio of shrinkage that occurs in the longitudinal direction of the fiber when the fiber of the present invention is heated at 100 ° C., and is obtained by the following equation.

Thermal shrinkage (%)
= Fiber length after heating (m) / Fiber length before heating (m) × 100
The fiber according to the present embodiment may have a heat shrinkage rate of 2% or more at 100 ° C., and it is estimated that the fiber is more rigid as the heat shrinkage rate is larger.

[Average birefringence]
In the present embodiment, the average birefringence can be measured using a commonly used compensator, and specifically, for example, can be measured by the method described in the examples described later.

The average birefringence of the fiber according to the present embodiment is preferably 30 × 10 ⁻³ or more, more preferably 40 × 10 ⁻³ or more, and further preferably 45 × 10 ⁻³ or more. . It is preferable that the average birefringence is in this range from the viewpoint of improving the mechanical strength of the fiber.

[Tensile strength]
In the present embodiment, the tensile strength can be measured using a commonly used tensile tester, and specifically, for example, can be measured by the method described in Examples described later.

  The tensile strength of the fiber according to the present embodiment is preferably 2.0 cN / dtex or more, more preferably 3.1 cN / dtex or more, and further preferably 4.0 cN / dtex or more. The tensile strength within this range is preferable from the viewpoint of improving the mechanical strength of the fiber.

[Tensile elongation]
In the present embodiment, the tensile elongation can be measured using a commonly used tensile tester, and specifically, for example, can be measured by the method described in the examples described later.

  The tensile elongation of the fiber according to this embodiment is preferably 50% or less, more preferably 40% or less, and even more preferably 25% or less. The tensile elongation in this range is preferable from the viewpoint of improving the mechanical strength of the fiber.

[Vinylidene fluoride resin]
In the present specification, the vinylidene fluoride resin means a polymer mainly composed of vinylidene fluoride (hereinafter also referred to as “VDF”) monomer. The vinylidene fluoride resin according to the present embodiment may be a vinylidene fluoride copolymer of a vinylidene fluoride monomer and another monomer, or a vinylidene fluoride composed of only one kind of vinylidene fluoride monomer. A homopolymer may be sufficient.

  The other monomer in the present invention is preferably at least one selected from the group consisting of hexafluoropropylene, trifluoroethylene, tetrafluoroethylene and chlorotrifluoroethylene.

  The vinylidene fluoride copolymer in the present invention preferably contains 90 mol% or more of vinylidene fluoride monomer, more preferably 97 mol% or more, and most preferably vinylidene fluoride homopolymerization. The content of the vinylidene fluoride monomer within this range is preferable from the viewpoint of improving the mechanical strength of the fiber.

(Inherent viscosity)
In this embodiment, the inherent viscosity can be obtained by dissolving a sample in dimethylformamide as a solvent and measuring the time during which a certain volume of liquid naturally falls in the capillary at 30 ° C. using an Ubbelohde viscometer.

  In this embodiment, the inherent viscosity of the vinylidene fluoride resin is preferably 0.70 dL / g or more and 0.95 dL / g or less, and is 0.75 dL / g or more and 0.90 dL / g or less. It is more preferable.

<Method for producing vinylidene fluoride resin fiber>
Hereinafter, one embodiment of a method for producing a fiber according to the present embodiment (hereinafter, also referred to as the present production method) will be specifically described, but the present production method is not limited to the following method.

  In this production method, for example, a plurality of filaments made of vinylidene fluoride resin are produced, and the fibers are obtained by integrating the filaments, and includes a discharging step, a spinning step, and a drawing step.

  As the vinylidene fluoride resin used in this production method, any of vinylidene fluoride copolymer and vinylidene fluoride homopolymer can be used. These vinylidene fluoride copolymers and vinylidene fluoride homopolymers can both be produced using conventional polymerization methods and apparatuses. Moreover, you may use a commercially available thing as a vinylidene fluoride copolymer and a vinylidene fluoride homopolymer, respectively.

  In the discharging step, the melted vinylidene fluoride resin is discharged into a fiber form from the spinneret to obtain an undrawn yarn of the vinylidene fluoride resin. At that time, the vinylidene fluoride-based resin can be melted at 240 ° C. to 270 ° C., for example. Further, the hole diameter of the spinneret (nozzle) may be appropriately adjusted depending on the inherent viscosity of the vinylidene fluoride resin to be discharged, and can be set to, for example, 0.10 to 1.00 mm.

  From the viewpoint of ensuring sufficient spinnability of the vinylidene fluoride resin, it is preferable to discharge the vinylidene fluoride resin while keeping the temperature at 70 to 155 ° C. in the discharge step. Such insulation of the vinylidene fluoride-based resin can be performed, for example, by keeping the temperature immediately below the spinning diameter for a certain period of time with a heating insulation cylinder.

  Furthermore, it is preferable to solidify the undrawn yarn of the vinylidene fluoride resin by cooling the discharged vinylidene fluoride resin. Thereby, it can extend | stretch efficiently in the next extending process. The method for cooling the vinylidene fluoride resin is not particularly limited, but air cooling is preferable from the viewpoint of simplicity.

  In the spinning process, the melt discharged in the discharging process is spun at a predetermined draft rate. Thereby, the low orientation undrawn yarn of a vinylidene fluoride resin can be obtained. The draft rate in the spinning process is preferably low, for example, 20 to 300.

  Then, the obtained vinylidene fluoride resin filaments are integrated with each other by, for example, bundling them with an oil ring or the like, and then the integrated vinylidene fluoride resin filaments are drawn in the drawing step. Thereby, the fiber which concerns on this embodiment is obtained.

  In the stretching step, the stretching temperature of the integrated vinylidene fluoride resin filament is, for example, 70 ° C to 165 ° C, preferably 80 to 160 ° C, and more preferably 100 to 155 ° C. The draw ratio is, for example, 2.50 times to 6.00 times, preferably 3.00 to 5.80 times, and more preferably 3.40 to 5.60 times.

  Furthermore, after the stretching process, post-treatment such as relaxation treatment or heat setting may be performed on the fiber. By performing these post-treatments, the thermal shrinkage of the fiber can be suppressed. Further, the post-treatment increases the crystallinity of the fiber and the amorphous becomes rigid, so that the strength of the fiber is improved. The relaxation temperature in the relaxation treatment is, for example, 100 to 180 ° C, preferably 110 to 170 ° C, and more preferably 120 to 165 ° C. Moreover, a relaxation rate is 0 to 20%, for example, Preferably it is 0 to 17%, More preferably, it is 0 to 15%. Moreover, the temperature in heat setting is 100-180 degreeC, for example, Preferably it is 110-170 degreeC, More preferably, it is 120-165 degreeC.

  According to this production method, the glass transition of the fiber obtained by setting the draft rate in the spinning process to 60 to 300, the stretching temperature in the stretching process to 80 to 155 ° C., and the stretching ratio to 3.0 to 5.50. While controlling temperature to -28 degreeC or more, the thermal contraction rate in 100 degreeC of the said fiber can be 2% or more.

  Further, by producing the fiber as described above, when the glass transition temperature of the fiber is −28 ° C. or higher and the thermal shrinkage at 100 ° C. is 2% or higher, the tensile strength is 2.0 cN / dtex. A fiber having a tensile elongation of 50% or less can be obtained.

Further, when the fiber obtained by producing the fiber as described above has a glass transition temperature of −27 ° C. or higher, and the heat shrinkage rate of the fiber at 100 ° C. of 3% or higher, the average birefringence. A fiber having a rate of 40 × 10 ⁻³ or more, a tensile strength of 3.1 cN / dtex or more, and a tensile elongation of 40% or less can be obtained.

  If it is such a fiber, it will be used suitably also for the sheet-like structure mentioned below, for example.

<Application of vinylidene fluoride resin fiber>
The vinylidene fluoride resin fiber according to the present embodiment may be further subjected to treatments such as antistatic, flame retardant, flameproof, antibacterial, deodorant, and deodorant treatments or various surface treatments as necessary.

  Moreover, the sheet-like structure which consists of a fiber which concerns on this embodiment can also be produced by giving the process of weaving, knitting, etc. using the vinylidene fluoride resin fiber which concerns on this embodiment. In this case, processing such as weaving and knitting can be performed using a conventional method and apparatus.

  Furthermore, the sheet structure according to the present embodiment may be formed in a mesh shape. In the sheet-like structure according to the present embodiment, the entire sheet may be formed in a mesh shape, or a part of the sheet may be formed in a mesh shape.

  The form of the sheet-like structure according to the present embodiment is not particularly limited, and can be used in various forms such as woven fabric, knit, string, cut fiber, paper, and nonwoven fabric. Also, its use is not particularly limited. For example, various industrial materials such as hollow fiber membrane reinforcing yarns, ropes and clothing, medical base materials, colored fibers, and piezoelectric bodies are suitably used for sensor devices. Can do. Moreover, when the sheet-like structure according to the present embodiment is formed in a mesh shape, the sheet structure can be suitably used as a fishing net, for example.

(Summary)
As described above, one aspect of the vinylidene fluoride resin fiber of the present invention is a fiber using a plurality of vinylidene fluoride resin filaments, and the fiber has a glass transition temperature of −28 ° C. or higher. The thermal shrinkage at 100 ° C. is 2% or more.

In one aspect of the vinylidene fluoride resin fiber of the present invention, the average birefringence is preferably 30 × 10 ⁻³ or more.

  In one embodiment of the vinylidene fluoride resin fiber of the present invention, the diameter of the filament is preferably 5 μm or more and less than 80 μm.

  In one aspect of the vinylidene fluoride resin fiber of the present invention, the vinylidene fluoride resin is preferably a homopolymer of a vinylidene fluoride monomer.

  In one embodiment of the vinylidene fluoride resin fiber of the present invention, the vinylidene fluoride resin is a vinylidene fluoride copolymer of a vinylidene fluoride monomer and another monomer, and the other monomer is hexagonal. It may be at least one selected from the group consisting of fluoropropylene, trifluoroethylene, tetrafluoroethylene, and chlorotrifluoroethylene.

  In one aspect of the vinylidene fluoride resin fiber of the present invention, the vinylidene fluoride copolymer preferably contains 90 mol% or more of the vinylidene fluoride monomer. In the vinylidene fluoride resin fiber of the present invention, the vinylidene fluoride resin fiber The resin is preferably a vinylidene fluoride homopolymer.

  In one embodiment of the vinylidene fluoride resin fiber of the present invention, the inherent viscosity of the vinylidene fluoride resin is preferably 0.70 dL / g or more and 0.95 dL / g or less.

  In one aspect of the vinylidene fluoride resin fiber of the present invention, it is preferable that the tensile strength is 2.0 cN / dtex or more and the tensile elongation is 50% or less.

In one aspect of the vinylidene fluoride resin fiber of the present invention, the average birefringence is 40 × 10 ⁻³ or more, the tensile strength is 3.1 cN / dtex, and the tensile strength is 40% or less. preferable.

  One aspect of the sheet-like structure of the present invention is one using the vinylidene fluoride resin fiber of the present invention.

  In one embodiment of the sheet-like structure of the present invention, for example, it may be formed in a mesh shape.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  Manufacture of the fiber of the vinylidene fluoride resin shown in each of the following Examples and Comparative Examples was carried out using a spinning device (manufactured by FIBER EXTRUSION TECHNOLOGY Inc.).

Example 1
As the vinylidene fluoride-based resin, pellet-shaped polyvinylidene fluoride (hereinafter also referred to as PVDF) (a KF polymer manufactured by Kureha Co., Ltd., melting point 173 ° C., inherent viscosity 0.85 dL / g) was used.

  PVDF was charged into a single-screw extruder (cylinder diameter: 25 mm) from a hopper of a spinning device, and PVDF was heated and melted at 265 to 270 ° C. The melted PVDF is spun at a draft rate of 120 from a 24-hole nozzle (hole diameter: 0.40 mm) using a gear pump to obtain 24 filaments made of PVDF, and then an oiling agent is applied and integrated to form PVDF. I got a fiber. Further, the fiber was drawn continuously at a drawing temperature of 80 ° C. and a draw ratio of 4.50, and then PVDF was relaxed at a relaxation temperature of 130 ° C. and a relaxation rate of 0% to obtain a stretched fiber made of PVDF.

(Example 2)
A fiber was obtained in the same manner as in Example 1 except that the drawing temperature was 130 ° C. and the draw ratio was 4.25.

(Example 3)
A fiber was obtained in the same manner as in Example 1 except that the drawing temperature was 130 ° C. and the draw ratio was 3.50.

Example 4
A fiber was obtained in the same manner as in Example 1 except that the drawing temperature was 130 ° C. and the draw ratio was 3.00.

( Reference Example 5)
A fiber was obtained in the same manner as in Example 1 except that the draft rate was 60, the stretching temperature was 100 ° C, the stretching ratio was 5.50, and the relaxation temperature was 100 ° C.

(Example 6)
A fiber was obtained in the same manner as in Example 1 except that the drawing temperature was 130 ° C, the draw ratio was 4.25, the relaxation temperature was 150 ° C, and the relaxation rate was 10%.

(Comparative Example 1)
Example 1 Except that the inherent viscosity of PVDF used in Example 1 was changed to 1.00 dL / g, the nozzle hole diameter in Example 1 was changed to 2 mm, the draft rate was 2550, and the fiber was not stretched. In the same manner, a fiber was obtained.

(Comparative Example 2)
The fiber obtained in Comparative Example 1 is discontinuous, that is, the unstretched fiber obtained in Comparative Example 1 is once wound up, and then the unstretched fiber thus wound is stretched at a temperature of 144 ° C. in another step. Then, the fiber was drawn at a draw ratio of 1.16 and drawn to obtain a fiber.

(Comparative Example 3)
A filament was obtained with a draft rate of 120 in Example 1.

  The fiber manufacturing conditions in Examples 1 to 6 and Comparative Examples 1 to 3 described above are summarized in Table 1 below.

<Evaluation of vinylidene fluoride resin fiber>
About each of the vinylidene fluoride resin fibers obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the filament diameter, average birefringence, glass transition temperature, heat shrinkage at 100 ° C., tensile Strength and tensile elongation were evaluated. The results are shown in Table 1. A specific evaluation method will be described below.

(Filament diameter)
An unstretched filament of PVDF having a length of 1 m was measured with a micrometer at 20 points, and an average value was obtained.

(Tensile strength and tensile elongation)
Using a tensile testing machine (manufactured by Tensilon Orientec Co., Ltd.), unstretched fiber (Comparative Example 1) was tested under the conditions of a test sample length of 100 mm and a crosshead speed of 300 mm / min, and the stretched fiber was tested. The sample length was 300 mm, the crosshead speed was 300 mm / min, and the measurement was performed 5 times. For the results of strength and elongation, the average of the breaking values (maximum points) was used.

(Glass transition temperature (Tg))
Using a dynamic viscoelasticity measuring device (DMS6100: manufactured by Seiko Eye Instruments Inc.), the test sample length is 3 mm, the frequency is set to 4 points of 0.5, 1.0, 5.0, and 10 Hz. Temperature range: -100 ° C. to 180 ° C. Temperature increase rate: measured at 2 ° C./min. The glass transition temperature (Tg) was defined as the peak temperature of dispersion derived from Tg appearing at a frequency of 10 Hz.

(Heat shrinkage at 100 ° C)
The sample 100m was raised on a rewinding machine having a frame circumference of 1 m, one end of the obtained skein was fixed, a weight of 20 g was applied to the other end, and the skein length L was measured. Next, the weight was removed, it was suspended in a dry heat oven at 100 ° C. and left for 30 minutes, and then cooled to room temperature. Thereafter, one end of the skein was fixed again, a weight of 20 g was applied to the other end, the skein length LHT was measured, and the dry heat shrinkage (%) was calculated by the following formula.
Dry heat shrinkage (%) = (L−LHT) / L × 100
Here, L represents the skein length (m) before heat treatment, and LHT represents the skein length (m) after heat treatment.

(Average birefringence)
The fiber was cut obliquely using a cutter, and a sample was prepared by dropping several drops of immersion liquid (Immersion Oil: n = 1.516 (23 ° C.)) on the cut surface of the fiber. The average birefringence (Δn) was determined by measuring retardation using a polarizing microscope and a Belek Compensator manufactured by Olympus Corporation.

  The vinylidene fluoride resin fiber of the present invention is, for example, in various forms such as woven fabric, knit, and string, various industrial materials such as fishing nets, hollow fiber membrane reinforcement yarns, ropes, clothing, medical base materials, coloring It can be suitably used as a fiber and a sensor device.

Claims (11)

  A fiber using a plurality of vinylidene fluoride resin filaments, the fiber has a glass transition point of −28 ° C. or higher and a thermal shrinkage at 100 ° C. of 2% or higher and 13.2% or lower. A vinylidene fluoride resin fiber characterized by that. 2. The vinylidene fluoride resin fiber according to claim 1, wherein an average birefringence is 30 × 10 ⁻³ or more.   The vinylidene fluoride resin fiber according to claim 1 or 2, wherein the filament has a diameter of 5 µm or more and less than 80 µm.   The vinylidene fluoride resin fiber according to any one of claims 1 to 3, wherein the vinylidene fluoride resin is a homopolymer of a vinylidene fluoride monomer.   The vinylidene fluoride resin is a vinylidene fluoride copolymer of a vinylidene fluoride monomer and another monomer, and the other monomers include hexafluoropropylene, trifluoroethylene, tetrafluoroethylene, and chlorotrifluoroethylene. The vinylidene fluoride resin fiber according to any one of claims 1 to 3, wherein the resin fiber is at least one selected from the group consisting of:   6. The vinylidene fluoride resin fiber according to claim 5, wherein the vinylidene fluoride copolymer contains 90 mol% or more of vinylidene fluoride monomer.   The vinylidene fluoride resin according to any one of claims 1 to 6, wherein the vinylidene fluoride resin has an inherent viscosity of 0.70 dL / g or more and 0.95 dL / g or less. Fiber.   The vinylidene fluoride resin fiber according to any one of claims 1 to 7, wherein the tensile strength is 2.0 cN / dtex or more and the tensile elongation is 50% or less. The average birefringence is 40 × 10 ⁻³ or more, the tensile strength is 3.1 cN / dtex or more , and the tensile elongation is 40% or less. The vinylidene fluoride resin fiber according to Item.   A sheet-like structure comprising the vinylidene fluoride resin fiber according to any one of claims 1 to 9.   The sheet-like structure according to claim 10, wherein the sheet-like structure is formed in a mesh shape.